Power Doppler ultrasonography for assessment of synovitis in the metacarpophalangeal joints of patients with rheumatoid arthritis - A comparison withdynamic magnetic resonance imaging

Objective. To evaluate the effectiveness of power Doppler ultrasonography ( PDUS) for assessing inflammatory activity in the metacarpophalangeal (MCP) joints of patients with rheumatoid arthritis (RA), using dynamic magnetic r esonance imaging (MRI) as a reference method. Methods. PDUS and dynamic MRI were performed on 54 MCP joints of 15 patient s with active RA and on 12 MCP joints of 3 healthy controls. PDUS was perfo rmed with a LOGIQ 500 unit by means of a 7--13-MHz linear array transducer. Later the same day, MRI was performed with a LOT MR unit. A series of 24 c oronal T1-weighted images of the second through the fifth MCP joints was ob tained, with intravenous injection of gadolinium diethylenetriaminepentaace tic acid after the fourth image (dynamic MRI). From the MR images, the rate of early synovial enhancement (RESE; defined as the relative enhancement p er second during the first 55 seconds postinjection) was calculated and com pared with the flow signal on PDUS, which was scored as present or absent. Results. In RA patients, flow signal on PDUS was detected in 17 of 54 MCP j oints examined. Postcontrast MR images revealed an RESE of greater than or equal to1.0%/second in 18 of 54 RA MCP joints. PDUS showed no now in 47 of 48 MCP joints with an RESE of <1.0%/second and revealed flow in 16 of 18 MC P joints with an RESE of <greater than or equal to>1.0%/second. Using dynam ic MRI as a reference, PDUS had a sensitivity of 88.8% and a specificity of 97.9%. Conclusion. PDUS was reliable for assessing inflammatory activity in the MC P joints of RA patients, using dynamic MRI as the standard. PDUS and clinic al assessment of joint swelling/tenderness were only weakly correlated.